<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    .demo {
      width: 100px;
      height: 100px;
      background: #fac;
    }
  </style>
</head>

<body>
  <div class="demo"></div>
  <script>
    var demo = document.getElementsByClassName('demo')[0];
    demo.onclick = function () {
      console.log('我被电击了');
      demo.onclick = null;
    }

    // addEventListener 无法解除匿名函数事件
    function click() {
      console.log('我被点击了');
      demo.removeEventListener('click', click);
    }
    demo.addEventListener('click', click);
  </script>
</body>

</html>